The University of Gießen is officially called Justus Liebig-Universität Gießen after its most famous faculty member, Justus von Liebig, the founder of modern agricultural chemistry and inventor of artificial fertiliser.

The University of Gießen was founded in 1607 as a Lutheran university in the city of Gießen in Hesse-Darmstadt because the all-Hessian Landesuniversität (the nearby University of Marburg (Philipps-Universität Marburg) in Marburg, Hesse-Kassel (or Hesse-Cassel)) had become Reformed (that is, Calvinist). The new university was called "Ludoviciana" after its founder Louis V, Landgrave of Hesse-Darmstadt and only renamed after World War II.

After the different Hessian states were (re-)united in 1929, both universities became public universities of that German state. The University of Gießen now has almost 23,000 students and 8,500 employees, which together with the Fachhochschule Gießen-Friedberg, makes Gießen the most student-dominated German city.

Next to Liebig, famous Gießen professors included the theologian Adolf von Harnack, the lawyer Rudolf von Jhering, the economist and statistician Etienne Laspeyres, the physicist Wilhelm Conrad Röntgen, the mathematicians Moritz Pasch and Alfred Clebsch, the gestalt psychologist Kurt Koffka, the philologist and archaeologist Friedrich Gottlieb Welcker, and the orientalist Eberhard Schrader. All of the most famous alumni of the university were born in Hesse-Darmstadt. They include the German romantic dramatist and revolutionary Georg Büchner, the literary and political historian Georg Gottfried Gervinus and the botanist Johann Jacob Dillenius.

The Holocaust Literature Research Unit of the University plans to publish My Opposition, the Friedrich Kellner World War II diary. Friedrich Kellner was chief justice inspector in Laubach from 1933 - 1950, and also district auditor for the region of Gießen.

Although the university has no defined campus, buildings and facilities are grouped together according to their subject areas and situated in various locations around Gießen. Philosophikum II, for example is an area on the outskirts of the city bordering the city forest. A number of faculty buildings and lecture theaters are located there, including Audimax, a building containing several lecture halls whose atrium is often the venue for concerts and disco-nights, locally known as "Uni-Partys."